Need help with small solar project

Thanks for all the tips, they are greatly appreciated.

Let's assume 7w and it runs 24hrs per day (as someone mentioned, far better to actually measure), that works out to 168w or about 14 amp-hr at 12v. Figure 20amp-hr to account for inefficiency. That results in needing a 40amp-hr battery as you can't take a lead acid battery below 50% without damage. Wouldn't be a bad idea to bump it up to 80amp-hr, so if you have a couple overcast days it doesn't kill the battery.

That's likely going to exceed what a lawn tractor battery can do. It might work for a week or so as the battery fully discharges but eventually it will kill the battery.

You might need to bump it up a touch for the charge controller. They don't take much but you are working with a really small system so it might be an impact.

If you go with a 12v camera, you can wire it directly to the battery without a converter which is simpler and more efficient.

As far as the solar panels, you need to put out about 200watt-hr per day. Figure you get about 4hr total of the rated output (it varies across the day and you almost never get the full rated output), so figure at least a 50w panel. Bumping up to 75w would be a good idea to help recover after an overcast day.

Check out Harbor Freight for a Solar system. or

Solar System for gate opner

gemsworld wrote:
For aesthetics reasons, I'm hoping a motorcycle or UPS backup battery will work so I can house all the necessary components in a small weather-resistant enclosure near the webcam.

Either will work, but neither are really the best for the job and may not have a long life. I don't know of any SMALL true deep discharge lead acid batteries.

Li-Ion is a possibility, but it will run your cost up ! First, you will need a charge controller that will handle Li-Ion batteries. Then you need the batteries themselves. Li-Ion batteries have a nominal 3.7V but must be charged at above 4.0V. so 4 Li-Ion batteries in series will need to be charged at more than 16.0 Your inverter might not like that. Adding 3 diodes in series between the positive of the battery pack will get you to about the proper voltage.

You will likely need 3 or 4 four battery packs, wired in parallel. Expensive, but they will last a very long time.

gemsworld wrote:
I came across this YT video that may help out rjxj with his trail cam:

Trail Cam Solar Panel DIY

Thank you. I subscribed. That voltage regulator is a nice find. That's where I went wrong with my set up.

I came across this YT video that may help out rjxj with his trail cam:

Trail Cam Solar Panel DIY

If you just want to buy something without math getting in the way, a 100 watt panel, cheap pwm controller and the biggest battery in your price range.

Something like a GoalZero kit would work, although they are wishy-washy on actual capabilities and capacities.

Thanks for the prompt replies.

The reason the wattage varies from 4 to 7 watts is based on the different cameras that I might use. Same for the 5 to 12V DC current.

For the sake of simplicity, what would I need in terms of solar panel and battery if I used a camera that uses a constant 7 watts 24/7?

It would be best to know the power demands for six days. Size the battery from that information, and then size the panels to keep the bank full.

Without knowing the energy needed any answer would be just a guess.

I used an earlier version of a Moultrie Power Panel to power an Wi-Fi POE bullet cam. The camera was not streaming. I used it to send photos to an ftp server when motion was sensed. I ended up moving the camera to a different location that had power available so I did not use it over a winter, but I do not believe the batter would last over night in the cold temperatures and limited sunlight of December & January.